1. Field of the Invention
This invention relates to vehicle seat belts, and more particularly, to a means for adjusting the shoulder restraint portion of a vehicle seat belt for individual comfort.
2. Background Information
The first seat belts in common use on passenger automobiles in the United States were simple lap belts which could easily be adjusted for length by sliding a portion of the buckling mechanism along one of these belts. As belts of this kind were gaining popularity, it became apparent that more lives could be saved and more injuries could be prevented through the addition of a shoulder belt. For example, automobile racing drivers using both lap belts and a shoulder harness could often survive severe crashes without serious injury. Thus, the shoulder belt was added to the lap belt of the American passenger car. Typically, the shoulder belt, like the lap belt, stretched between two anchor points in the vehicle, with a buckle system which could be adjusted to vary the effective length of the belt. While the independent length adjustments of the lap and shoulder belts made it easy to perform these adjustments as required for the individual driver or passenger, a problem was typically encountered in that the angle at which the shoulder belt pulled across the body of the driver or passenger could not be adjusted, since the two anchor positions of the shoulder belt were at fixed locations in the vehicle. The use of these locations sometimes meant that the shoulder belt would pull across the side of the neck of the driver or passenger. Many people who felt the shoulder belts were uncomfortable, or that they were too much trouble, simply did not use them. A method for simplifying the use of the shoulder belt, together with means for providing additional adjustability was needed.
The next generation of belts used on automobiles and other vehicles combined the functions of lap and shoulder belts. In a popular type of belt assembly, a first web of belt material was fed downward from an upper reel, across the outer shoulder of the driver or passenger, to a buckle mechanism fastened to an anchor point near the center of the vehicle. A second web of belt material was fed upward from a lower reel, across the lap of the driver or passenger, to the same buckle mechanism. Thus, while separate reels were required to provide for the supply and tension control of the shoulder belt web and the lap belt web, the operation of a single buckle mechanism by the user held both webs in place. While a method was still not provided for varying the angle at which the shoulder belt extended across the user, a feature in the reel mechanism used to tension this belt allowed the user to release the tension of the shoulder belt by pulling it away from his chest. In this way, someone who was bothered by the angle of the shoulder belt could at least alleviate the problem by producing slack in the belt. Unfortunately, the gap resulting from this slack was found to reduce substantially the effectiveness of the shoulder belt for preventing death and injuries in accidents.
The present generation of seat belts uses a single web of belt material to form both a lap belt and a shoulder restraint. Adjacent to the outside edge of the seat, the web of belt material extends upward from a reel to an upper guide fastened to an upper anchor. From the upper guide, the web also extends downward and inward from the reel to a lower guide, which is removably fastened to a lower anchor by a latch. From the lower guide, the web extends outward across the seat to a lower anchor. While this system maintains tension in both the shoulder restraint and in the portion of the belt extending across the lap, sufficient adjustment is not provided for comfortable use. Particular problems are encountered by many individuals in the use of the shoulder restraint portion of the seat belt system, due to the fact that this portion crosses their bodies too close to their necks. Many people cite this type of discomfort as a reason for not wearing their belts. What is still needed is a means to adjust the angle at which the shoulder restraint lies across the body of a driver or passenger.